From the riotous hanging basket to the single plant in a simple terracotta pot, pelargoniums get every-where in summer. The best-known types are upright and uptight pompoms of brilliant colour, but others have variegated leaves and pastel flowers, and far more relaxed shapes. Whatever your chosen style or colour scheme, no window box or container is complete without them.

First, a little clarification: pelargoniums — the bedding plants you put out in late spring and bring inside in autumn - are commonly known as geraniums, but geraniums they ain't. The true botanical geranium is the hardy border plant found in every herbaceous border, and is an entirely different genus.

Back before botanists had eyes, they grouped pelargoniums and geraniums together under the name Geranium. They later changed their minds, but the confusion continues. It is useful to know the difference if you intend to buy pelargoniums, but be prepared for the sales assistant to stare at you blankly and to end up asking for geraniums anyway.

Pelargoniums are great "friendship plants", because the cuttings are easy for even the most inexperienced gardeners to take, and will root at any time. Cuttings should be a few inches long and contain several nodes (the lumpy bits where the leaves emerge), and your cut should be made just below the lowest node. Remove the bottom few leaves, then push the cutting into some seed and cutting compost and mist lightly with water (pelargoniums' succulent stems rot easily, so keep the soil just moist). Keep them in a bright spot and pot on when they start to produce new shoots. Remove any flowers that start to form while the plant is small - this will help it put all its energy into growth, and you will get a good-sized plant sooner.

As they start to grow, all types of pelargonium benefit from having their growing tips removed back to the point where leaves emerge. This helps keep them bushy and compact.

Old, established plants that have got leggy and woody, meanwhile, can be revitalised. In spring, pot them on into a slightly larger pot with fresh compost on top, then cut them back to where small shoots emerge from the stem. Eventually, you should replace them with new cuttings.

Even pelargoniums that are grown primarily as house plants will benefit from a spell outdoors in summer. With a bit of fresh air and rainwater, they will put on lots of fresh new growth. Remove the flower spikes right down to their base as soon as they have started to look tatty - this will encourage more to form.

For a really floriferous effect, put pelargoniums in full sun. They should be fed every couple of weeks over summer, and watered carefully. Plants grown alone will not need water until their compost has almost dried out; water those in mixed baskets more, because the other plants will suffer sooner.

Even without their many charms, pelargoniums would be worth growing for one reason alone: theirs will be one of the few containers still flowering and looking good after your fortnight's holiday in Cornwall.

PELARGONIUMS TO LOOK OUT FOR

Zonal pelargoniums The classic bedding pelargonium — such as the pillarbox-red, drumstick-flowered 'Robe' — is a zonal type. It has an urban smartness, and suits being neatly arranged in individual terracotta pots along a wall or windowsill, or used as a centrepiece for a colourful mixed container or window box, combined with plants such as petunias, lobelia and verbena. As well as double- and single-flowered types, there are also 'stellars', with thin, spiky petals, leaves and flowers, and tulip-flowered, cactus-flowered and rosebud types. The only zonals not primarily grown for their flowers are the fancy-leaved varieties. Their leaves have cream, white, red, pink, dark and light green zones, and the flowers often tone in beautifully (but can occasionally clash horribly). 'Mont Blanc' is very pretty, with pure white and green foliage, and white flowers.

Regal and angel pelargoniums The huge, frilly petalled flowerheads of regal pelargoniums make them popular bedding and house plants, but they are a bit frou-frou. They're usually grown on their own. Angel pelargoniums are miniature versions of regals, developed for their pansy-shaped flowers.

Ivy-leaved pelargoniums The leaves have a shiny, sculptured look, and a graceful, trailing habit. The best of the flowers are deep maroons and pale pinks, but I particularly love 'Mexicana' (left), the petals of which have a dark red outline and pale interior, making the whole flower look like a flamenco dancer's skirt. Ivy-leaved pelargoniums can be mixed in with other plants; in fact, they look great trailing over the edges of window boxes or next to other strongly shaped plants such as cordylines. But to be appreciated fully, they should be grown alone, preferably in a terracotta pot against a sun-baked wall.

Scented-leaved pelargoniums Most often grown as houseplants, because they emit delicious lemon, orange and rose scents when rubbed or even just watered. They also make classy bedding. Try a variegated type, such as 'Lady Plymouth', in pots placed either side of a front door. All are primarily foliage plants, and so have small, subtly coloured flowers. Pelargonium crispum 'Variegatum' has variegated leaves and a lemon scent, while P. tomentosum has furred leaves that smell of peppermint.

· Readers can order two pelargonium collections: Ivy (three each of 'Mexicana' and 'Blanche Roche') for £6.95; or Stellars (three each of 'Fireworks Salmon' and 'Fireworks Light Pink') for £6.95. Or buy both for £9.90. Plants delivered as 4cm plugs. Call 0870 836 0900, quoting ref GULL01. Price includes UK mainland p&p. Plants dispatched within 28 days.